The trouble with H0

By J. Bernal, L. Verde, A. Riess. 2016

635 citations recorded by the source corpus.

We perform a comprehensive cosmological study of the H0 tension between the direct local measurement and the model-dependent value inferred from the Cosmic Microwave Background. With the recent measurement of H0 this tension has raised to more than 3 σ. We consider changes in the early time physics without modifying the late time cosmology. We also reconstruct the late time expansion history in a model independent way with minimal assumptions using distance measurements from Baryon Acoustic Oscillations and Type Ia Supernovae, finding that at z < 0.6 the recovered shape of the expansion history is less than 5% different than that of a standard ΛCDM model. These probes also provide a model insensitive constraint on the low-redshift standard ruler, measuring directly the combination rsh where H0 = h × 100 Mpc−1km/s and rs is the sound horizon at radiation drag (the standard ruler), traditionally constrained by CMB observations. Thus rs and H0 provide absolute scales for distance measurements (anchors) at opposite ends of the observable Universe. We calibrate the cosmic distance ladder and obtain a model-independent determination of the standard ruler for acoustic scale, rs. The tension in H0 reflects a mismatch between our determination of rs and its standard, CMB-inferred value. Without including high-ℓ Planck CMB polarization data (i.e., only considering the ``recommended baseline" low-ℓ polarisation and temperature and the high ℓ temperature data), a modification of the early-time physics to include a component of dark radiation with an effective number of species around 0.4 would reconcile the CMB-inferred constraints, and the local H0 and standard ruler determinations. The inclusion of the ``preliminary" high-ℓ Planck CMB polarisation data disfavours this solution.

Subfields: Astronomy and Astrophysics, Genetics, Speech and Hearing

View Paper: https://www.semanticscholar.org/paper/e05b2a086aed74a3fe5f92ca779f8b69a7fe927a

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Citations in the corpus

A buyer’s guide to the Hubble constant (2021, background): “We also note that the logic explained above to derive H0 can be reversed: BAO can be combined with a H0 prior from nearby universe results, instead treating the sound horizon rd as a free parameter (Bernal et al. 2016).”
Nonminimal dark sector physics and cosmological tensions (2019, background): “046) [42–44].”
New physics in light of the H0 tension: An alternative view (2019, background): “046, where Neff is the effective number of relativistic species) [58, 59].”
Challenges and opportunities of gravitational-wave searches at MHz to GHz frequencies (2020, background): “Early Universe and late time observations report slightly different values for hH , see Bernal et al. (2016) for a discussion.”
On the Hubble Constant Tension in the SNe Ia Pantheon Sample (2021, background): “Another suggestion is to make changes in the earlytime universe without modifying the late-time cosmology (Bernal et al. 2016).”
Refined bounds on MeV-scale thermal dark sectors from BBN and the CMB (2019, methodology): “Since the disagreement between local [119] and CMB determinations of the Hubble constant [7] could potentially be attributed to additional contributions to Neff [120, 121], we consider two data sets: i) in which we consider the 2018 Planck baseline TTTEEE+lowE analysis and ii) where we combine Planc”
Dark Energy in Light of Multi-Messenger Gravitational-Wave Astronomy (2018, result): “4 eases the tension but enters in conflict with small scale Planck polarization (Bernal et al., 2016b), which has been confirmed in the latest Planck results.”
Does the Hubble constant tension call for new physics? (2018, methodology): “radiation refers to any relativistic energy component with none or negligible electromagnetic interactions. Early dark radiation may aect CMB uctuations at small scales by changing the damping scale [23]. In principle, this can be remedied by allowing for a scale dependence in the spectral tilt, n, ”
Cosmology with a very light Lμ − Lτ gauge boson (2019, background): “Such a discrepancy could be ameliorated if the expansion rate of the universe departed from the predictions of standard ΛCDM cosmology at early times [9, 10].”